Facile access to 2-hydroxy-2-substituted indole-3-ones via a copper-catalyzed oxidative cyclization of 2-arylethynylanilines

Abstract

This paper reports a practical and versatile oxidative cyclization of 2-arylethynylanilines towards 2-hydroxy-2-substituted indol-3-ones via a copper-catalyzed radical approach in the presence of O2. The transformation of 2-hydroxy-2-arylindol-3-ones to 3-hydroxy-3-arylindol-2-ones...

Copper–Catalyzed Construction of the Indole Core: Recent Advancements

“…Oxidative cyclization of o ‐alkynylanilines 30 could be performed via copper catalyzed radical approach to obtain 2‐hydroxy‐2‐aryl indol‐3‐ones 31 [63] . Here, oxygen (O 2 ) was employed as an external oxidant.…”

“…Notably, the coupled five-six aromatic rings were generated through the selective formation of two C(sp Oxidative cyclization of o-alkynylanilines 30 could be performed via copper catalyzed radical approach to obtain 2hydroxy-2-aryl indol-3-ones 31. [63] Here, oxygen (O 2 ) was employed as an external oxidant. The strategy was to use an electron-withdrawing substituent, such as acyl, to reduce the nucleophilicity of the amino group of 30, so that the formation dehydrated intermediate 32 can be prohibited.…”

Radical Cyclization-Initiated Difunctionalization Reactions of Alkenes and Alkynes

“…A Cu-catalyzed reaction of 2-arylethynylanilines for the synthesis of substituted 2-hydroxy-2-indol-3-ones was reported by Wu, Chen and their coworkers in 2023. The reaction of 2-arylethynylanilines 432 and O 2 in the presence of Cu(OTf) 2 , Zn(OTf) 2 and 6,6′-dimethyl-2,2′-bipyridine CH 3 CN/HFIP (hexafluoro- iso -propanol) at 60 °C for 17–24 h afforded substituted 2-hydroxy-2-indol-3-ones 433 in good yields ( Scheme 87 ) [ 111 ]. This reaction could be carried out at a gram-scale under the standard conditions to give product 433a in 69% yield.…”